The Shanghai district is situated in 30˚23′--31˚37′N. and 120˚50′-121˚45′E. It is bounded on the northeast by Jiangsu Province and on the southwest by Zhejiang Province. It has a total area of more than 6000km2.The flora of the hills and hillocks in the Shanghai district such as Sheshan and Dajinshan is composed mainly of plants of the Fagaceae, Lauraceae, Theaceae, Juglandaceae, Rosaceae and Gramineae. The evergreen broadleaf forests is composed mainly of the species Cyclobalanopsis glauca, Machilus thunbergii, Castanopsis sclerophylla and the subtropical bamboo groves of the species Phyllostachys congesta are the zonal vegetation of Shanghai. Now, secondary growth of the species Quercus fabri and various kinds of shrubs are widely distributed in the district of Shanghai.The northern boundary of the zone of central subtropical evergreen broadleaf forests in the territory of Shanghai should be the line formed by Gangshen, namely the line running from Waigang through Nanxiang, Xinzhang, Maqiao, and Zhelin to Chaojin.

Vegegraphy, a newly-created term in this paper and a compound word of prefix “vege-” of “vegetation” and suffix of “-graphy”, is a series of monographs that describe detailedly species composition, structures, functions, environmental settings, and distribution of a set of plant communities and/or their combinations for each vegetation type, using community data from vegetation survey. Its compilation is very huge, comprehensive, time-consuming research project, and great importance in the ecological research, vegetation restoration and utilization, biodiversity conservation, and environmental monitoring. This article first documents major community characteristics (i.e., species composition, structures, physiognomy, and dynamics), and historical development and current state of vegetation survey in China and worldwide, then reviews historical studies on vegetation classification systems and their revisions, and finally discusses compilation of vegetation of China and classification of vegetation types used for the compilation. For the revision of vegetation classification systems, we mainly revised high-level units of previous classification systems and the corresponding English terms. Following this revised classification system, the hierarchical level of China’s vegetation classification is expressed as high-level units (Vegetation Formation Group, Vegetation Formation, and Vegetation Subformation), medium-level units (Alliance Group, Alliance, and Suballiance), and lower-level units (Association Group and Association), respectively. In the Vegetation Formation Group unit, nine types were divided as Forest, Shrubland, Herbaceous vegetation, Desert, Swamp & Aquatic Vegetation, Alpine Tundra & Sparse Vegetation, Cultivated Vegetation, Urban Vegetation, and Non-Vegetated Area. For the compilation of vegetation of China and the classification of vegetation types, we used the high-level unit, Vegetation Formation, as the Volume of the vegegraphy, and used a specific term, “Vegetation type”, as the Issue under the Volume. The Vegetation type here is not a real vegetation classification unit but is a combination of a set of vegetation units (i.e., Vegetation Subformation and/or Alliance Group and/or Alliance) in which there exist the same or similar constructive species or the same dominant taxa (species or genus) in the communities. The determination of “Vegetation type” follows the four principles: identity of dominant taxa and life form, relative importance of habitats, difference of vegetation characteristics and application, and practicability of vegegraphy. As a result, the vegetation of China (Vegegraphy of China) completed will be composed of 48 volumes and about 110 issues.

In recent years, the relationship of biodiversity to ecosystem stability, productivity and other ecosystem functions have been researched by using theoretical approaches, experimental investigations and observations in natural ecosystems,however, results have been controversial. For example, simple systems were more stable than complex systems in theoretical studies, higher productivity was observed in man-made ecosystems with poorer species composition than in natural ecosystems with more diverse assemblages, etc. The role of biodiversity in ecosystem functioning, such as its influence on sustainability, stability, and productivity, still is not understood. Because accelerated soil erosion in various ecosystems has caused a decrease in ecosystem primary productivity, a logical way to study the relationship between biodiversity and ecosystem function will be to study the relationship between plant species diversity and soil conservation. In addition, biodiversity is a product of evolutionary history and soil erosion is a key factor controlling the evolution of the modern environment on the surface of the Earth. A study on the relationships between biodiversity and soil erosion processes could help to understand the environmental evolution of Earth and predict the future changes.

To test this, fifteen 10 m×40 m standard runoff plots were established to measure surface runoff, soil erosion and total P leaching in different secondary communities of semi-humid evergreen broad-leaved forests that varied in composition, diversity and level of disturbance and soil erosion. The following five communities were studied: AEI (Ass.Elsholtzia fruticosa+Imperata cylindrical), APMO (Ass. Pinus yunnanensis+Myrsine africana+Oplismenus compsitus), APLO (Ass.Pinus yunnanensis+Lithocarpus dealbatus+Oplismenus compsitus), AEME (Ass. Eucalyptus smith+Myrsine africana+Eupatorium enophorum) and ACKV (Ass. Cyclobalanopsis glaucoides+Keteleeria evelyniana+Viola duelouxii) in central Yunnan Province of China (101°28'18″ E, 25°24'09″ N, 1 950-2 015 m). Tree density, the diameter of trees at breast height and the hygroscopic volume of plant leaves were determined in each plot in order to analyze the relationship between plant species diversity and ecosystem function related to soil conservation and community structure. The degraded AEI, APMO, APLO and ACKV communities were restored naturally and the AEME was restored using plantation trees ofE. smith and E. maidenii at AEI. The sequence of the successional phases were: 1) AEI AEME ACKV; 2) AEI APMO APLO ACKV. The slope degree, slope position and soil types of all plots were similar so that the results of these plots could be compared based on differences in diversity and composition only.

The results indicated that surface runoff, soil erosion and total P leaching decreased according to a power function as plant species diversity increased and the three year average was 960.20 m³·hm^-2·a^-1, 11.4 t·hm^-2·a^-1, 127.69 kg·hm^-2·a^-1 in the plot with the lowest species diversity and 75.55 m³·hm^-2·a^-1, 0.28 t·hm^-2·a^-1, 4.71 kg·hm^-2·a^-1 in the plot with the highest species diversity. The low species plot was 12, 50 and 25 times, respectively, higher than in the high species plot. Soil conservation was enhanced with increasing plant species diversity. The coefficient of variation of surface runoff, soil erosion and total P leaching also followed a power function decreasing with increasing plant species diversity from 2001 to 2003. The coefficient of variation was 287.6, 534.21, 315.47, respectively, in the lowest species diversity plot and 57.93, 187.94 and 59.2 in the highest species diversity plot, which was 4, 3 and 5 times greater in the lowest species plot. Enhanced soil conservation maintained greater stability with increased plant species diversity. Plant individual density increased linearly and the degree of closeness and basic coverage increased logarithmically with increasing plant species diversity. The hydrological function of the leaves of the plant communities was strongest in ACKV, poorest in APMO, and intermediate in the AEME, APLO and AEI communities. The hydrological function of the leaves was enhanced as the plant species diversity increased. There were obviously relationships between plant species diversity with rainfall interception, coverage, plant individual density and they were related to soil conservation once more in the five successional forest communities.

The complex relationships of plant species diversity with above-mentioned ecological processes indicated that plant species diversity was an important factor influencing the interception of rainfall reducing soil erosion and enhancing the stability of soil conservation, but the causal mechanism is not known. This experiment showed that plant species diversity promoted soil and nutrient conservation and was able to predict primary productivity of the ecosystem, and was thus a good way to study the relationship between biodiversity and ecosystem stability. Rainfall interception could be assessed easily using the hygroscopic volume of plant leaves of the plant community. Because there were strong correlations between plant species diversity and ecosystem functioning as related to soil conservation, the patterns of plant species diversity will show a certain level of predictability on the interactions of life systems with surface processes of the Earth.

A central goal of community ecology is to understand the forces that maintain species diversity within communities. The traditional niche-assembly theory asserts that species co-occur in a community only when they differ from one another in resource use. But this theory has some difficulties to explaining the diversity often observed in species-rich communities such as tropical forests. As an alternative to niche theory, Hubbell and other ecologists introduced a neutral model. Hubbell argues that the number of species in a community is controlled by species extinction and immigration and speciation of new species. Assuming that all individuals of all species in a trophically similar community are ecologically equivalent, Hubbell's neutral theory predicts two important statistical distributions. One is the asymptotic log-series distribution for the metacommunity under point mutation speciation, and the other is the zero-sum multinomial distribution for both local community under dispersal limitation and metacommunity under random fission speciation. Unlike the niche-assembly theory, the neutral theory takes similarity in species and individuals as a departure for investigating species diversity. Based on the fundamental processes of birth, death, dispersal and speciation, the neutral theory first presented a mechanism that generates species abundance distributions remarkably similar to those observed in nature. Since the publication of the neutral theory, there has been much discussion of it, pro and con. In this paper, we summarize new progresses in research on assumption, prediction and speciation mode of neutral theory, including progress in the theory itself and tests about the theory's assumption, prediction and speciation mode at metacommunity level. We also suggest that the most important task in the future is to bridge the niche-assembly theory and the neutral theory, and to add niche-differences in neutral theory and more stochasticity into niche theory.

Samara (winged fruit) can be dispersed easily by wind and may be a crucial factor for angiosperm spread and diversification. In a narrow sense, a samara is an indehiscent dry fruit with wing(s) developed from fruit pericarp, while in a broad sense samaras also include all winged fruits with wings developed from both pericarp and perianth or bracts. According to the wing shape and growth patterns of samaras, we divided samaras into six types, i.e. single-winged, lanceolate-winged, rib-winged, sepal-winged, bract-winged, and perigynous samaras. Perigynous samaras can be further classified into two forms, i.e. round-winged and butterfly-winged samaras. Accordingly, the aerodynamic behavior of samaras can be classified into five types, autogyro, rolling autogyro, undulator, helicopter, and tumbler. The rib-winged and round-winged samaras can be found in Laurales, a basal angiosperm, and may represent the primitive type of early samaras. In the derived clades, samaras evolved enlarged but unequal wings and decreased wing loading (the ratio of fruit weight to wing size), which is likely an adaptation to gentle wind and secondary dispersal through water or ground wind. The wings of some samaras (such as sepal-winged and bract-winged samaras) may have multiple functions including wind dispersal, physical defense for the seeds, and adjust seed germination strategy. The pantropical family Malpighiaceae is extraordinarily rich in samara types, which is likely related to its multiple inter-continent dispersal in history, which is known as “Malpighiaceae Route”. Therefore, Malpighiaceae can be used as a model system for the studies on samara adaptation and evolution. We identified the following issues that deserve further examination in future studies using both ecological and evo-devo methods: 1) the adaption of different types of samaras in dispersal processes, 2) the molecular and developmental mechanism of sepal- and bract-wings, and 3) the evolution of samara types and their effects on angiosperm diversification.

Eupatorium adenophorum, native to Mexico and Costa Rica of Central America, is a worldwide noxious invasive weed. It occurs throughout many terrestrial areas of the world and is especially rampant in Southeast Asia, Hawaii (U.S.), New Zealand, Australia, and the Pacific Islands. Since its invasion to China from the boundaries of Vietnam and Burma, the speed of its spread has been faster than anticipated, particularly in the southern and southwestern parts of the country. Presently, E. adenophorum can be found in Chongqing, Yunnan, Sichuan, Guizhou, Tibet, Guangxi, Taiwan and Hubei Provinces. A rough estimate of the annual spreading rate of E. adenophorum is about 10-60 km from south to north and from west to east in China. It is considered a threat to local economy and biodiversity. As a result, an increasing number of Chinese scientists have become interested in studying this species and much progress in understanding the biology and ecology of this species has been made to date. In particular, much is known about the underlying mechanisms of its invasion biology.
This paper reviews some of the hot research topics of this invasive species in China, including its distribution, predicting its potential distribution, the mechanisms underlying its invasion and spread, and methods for control and elimination. The distribution of this invasive plant in China has been mapped and its potential distribution has been predicted using a computer model based on climatic factors.
Among current research efforts, understanding the mechanisms underlying its invasion and spread is one of the hottest topics. Recent research also has studied the patterns of genetic variation within populations of the invasive weed, novel biochemical mechanisms of interspecies interactions, biological characteristics of the invasive species that explain its highly successful spread, e.g., small seed size, persistent soil seed bank, high offspring production, potential long-distance dispersal of propagules, vegetative reproduction, relatively high CO₂ fixation capacity, shade tolerance, high adaptive ability, and tight link of life-history traits with climatic rhythm.
Although much progress in understanding the biology and ecology of this species has been achieved, there have been no dramatic breakthroughs on how to control E. adenophorum so far. At present, control methods of E. adenophorum are divided into three general categories: manual, chemical and biological control. Biological control is considered the most promising sustainable control strategy for this weed. Several natural enemies and pathogens have been reported that might be able to control the reproduction of this weed, such as Procecidochares utilǐs, Cercospora eupatorii and Alternaria alternata.
The current status of research on the invasive species, E. adenophorum, was reviewed in this paper. Five areas of future research have been proposed: 1) modeling long-distance seed dispersal; 2) allelopathic mechanisms of invasion; 3) ecophysiological adaptations of the invasive species; 4) breeding system of the invasive species; and 5) effective biological control of the invasive species, especially the potential role of genetically engineered fungi.

Plant traits link environmental factors, individuals and ecosystem structure and functions as plants respond and adapt to the environment. This review introduces worldwide classification schemes of plant functional traits and summarizes research on the relationships between plant functional traits and environmental factors such as climate (e.g., temperature, precipitation and light), geographical variation (e.g., topography, ecological gradients and altitude), nutrients and disturbance (including fire, grazing, invasion and land use), as well as between plant functional traits and ecosystem functions. We synthesize impacts of global change (e.g., climate change) on plant functional traits of individuals and plant communities. Research on plant functional traits is very fruitful, being applicable to research on global change, paleovegetation and paleoclimate reconstruction, environmental monitoring and assessment and vegetation conservation and restoration. However, further studies at large scale and including multi-environmental factors are needed and methods of measuring traits need to be improved. In the future, study of plant functional traits in China should be accelerated in a clear and systematic way.

Jiangsu Province is situated at the sea board of Yellow sea, in latitute 30?46′—35?07′ north, longitude 116?22′—121 ?55′ east. It lies on the transitional area of warm temperate and subtropic zones, extending across southern temperate, northern subtropic and central subtropic bioclimatic belts. The annual mean temperature is 13–16℃, annual mean precipitation is 800–1200mm. There are uplifted hills and low mountains, which occupy about 5% of the total area, majority of them has an elevation of 200--300m. in general. The highest mountain in the area, Yun Tai Shan is mere at an elevation of 625m.By analysing the data, chiefly obtained by our own field survey, we recognize that, the basic characteristics of zonal vegetation in Jiangsu Province and its distribution pattern may be briefly summarized as follows:There are three typical zonal vegetation types in Jiangsu Province:1. The deciduous broad-leaved forestIt is mainly distributed in the north warm temperate region of the province and also may be seen in northern subtropic region. The basic constructive species for deciduous broad-leaved forest belong to the family Fagaceae, including Quercus variabilis, Q. fabri, Q. acutissima, Q. serrata var. brevipetiolata etc. In the calcareous hills, the species of Ulmaceae, such as Celtis bungeana, C. biondii, Ulmus pumila, U. parvifolia etc. are the characteristic species. 2. The deciduous and evergreen mixed forest It is widely distributed in the northern subtropic region of the province, but the typical form occupies the dotting hills along the edges of Taihu lake and the low mountains of Yixing and Liyang Districts, mainly in the central subtropic region. The basic constructive species for deciduous and evergreen mixed forest also belong to the family Fagaceae. The deciduous species are Quercus variabilis, Q. fabri, Q. acutissima, Q. serrata var. brevipetiolata etc. while the evergreen species are Castanopsis sclerophylla, Cyclobalanopsis glauca etc. Some calciphilous species such as Ulmus spp., Celtis spp., Zelkova schneideriana, Aphananthe aspera, Pteroceltis tatarinowii etc occurred on the calcareous hills. We consider that the deciduous and evergreen mixed forest type is a transitional form. This type is distributed overwhelmingly in the transitional area, the northern subtropic zone between warm temperate and subtropic zones of China, consequently it is distinguished with transitional characteristics, which are remarkably reflected by the development of mixed forest formation and its wide occurrence. 3. The evergreen broad-leaved forestIt is merely distributed in the central subtropic region of the province mainly in the mountainous regions of Yixing and Liyang Districts. The basic constructive species for evergreen broad-leaved forest are the evergreen trees of the family Fagaceae, such as Castanopsis sclerophylla, C. carlesii, Cyclobalanopsis glauca. C. myrsinaefolia, Lithocarpus glabra etc. In this forest, the deciduous spices are usually more in number than the evergreens, but the abundance and coverage of the latter are certainly dominant, therefore we consider that the evergreen broad-leaved forest type at the northern fringe of central zone is usually ,with some transitional characteristics. The principal types of three typical zonal vegetation types mentioned above are tabulated in detail. According to data of many plots, the dominant and frequent species, crown density distribution and habitat of all communities have been respectively generalized. Owing to having no high mountains the vertical zonation of vegetation does not exist. But the zonal vegetation types extending across three bioclimatic belts appear evidently. From north to south, the floristic component of zonal vegetation are gradually becoming multified, the number of vegetation types is increasing and zonal vegetation patterns occur successively in the order of the deciduous broad-leaved forest type, the deciduous and evergreen mixed forest type and the evergreen broad-leaved forest type. The typical zonal vegetation types of southern temperate, northern subtropic and central subtropic belts of China are tentatively designated as deciduous broad-leaved forest type, deciduous and evergreen mixed forest type and evergreen broad-leaved forest type respectively. The preceding two types containing the secondary vegetation, may also occur in northern and central subtropic belts respectively.

Aims Net primary productivity (NPP) is a key component of the terrestrial carbon cycle. Model simulation is commonly used to estimate regional and global NPP given difficulties to directly measure NPP at such spatial scales. A number of NPP models have been developed in recent years as research issues related to food security and biotic response to climatic warming have become more compelling. However, large uncertainties still exist because of the complexity of ecosystems and difficulties in determining some key model parameters.
Methods We developed an estimation model of NPP based on geographic information system (GIS) and remote sensing (RS) technology. The vegetation types and their classification accuracy are simultaneously introduced to the computation of some key vegetation parameters, such as the maximum value of normalized difference vegetation index (NDVI) for different vegetation types. This can remove some noise from the remote sensing data and the statistical errors of vegetation classification. It also provides a basis for the sensitivity analysis of NPP on the classification accuracy. The maximum light use efficiency (LUE) for some typical vegetation types in China is simulated using a modified least squares function based on NOAA/AVHRR remote sensing data and field-observed NPP data. The simulated values of LUE are greater than the value used in the CASA model and less than the values simulated with the BIOME-BGC model. The computation of the water restriction factor is driven with ground meteorological data and remote sensing data, and complex soil parameters are avoided. Results are compared with other studies and models.
Important findings The simulated mean NPP in Chinese terrestrial vegetation from 1989-1993 is 3.12 Pg C (1 Pg=10¹⁵ g). The simulated NPP is close to the observed NPP, and the total mean relative error is 4.5% for 690 NPP observation stations distributed in the whole country. This illustrates the utility of the model for the estimation of terrestrial primary production over regional scales.

The ability for vegetation and soil organic matter (SOM) to sequester atmospheric CO 2 has received a lot of attention recently. Two management options being considered for enhancing C sequestration from the atmosphere include tropical forest conservation and establishment of plantations; however, there is still considerable debate regarding the appropriateness of using plantations and the sequestration potential of tropical plantations. There are 1.3×10 5 hm 2 of rubber trees (Hevea brasiliensis) plantations in Xishuangbanna, southwest China, which account for approximately 14% of the forest lands in this region. In this study, eleven plantations of different ages were selected to investigate C sequestration in the vegetation and soils following the establishment of rubber tree plantations on former arable lands. The results indicated that the average biomass growth rates of the rubber trees, calculated according to two different biomass growth equations, were 10.2×10 3 and 9.4×10 3 kg t·hm -2 ·a -1. Soil C stocks in the top 40 cm and 1 m of soil increased at rates of 0.61×10 3 and 0.72×10 3 kg t C·hm -2 ·a -1, respectively. In total, C sequestration was approximately 5.82×10 3 to 5.42×10 3 kg t C·hm -2 ·a -1 in the vegetation and soil as calculated by the two biomass growth models. When comparing the two models, our results showed that the biomass calculated based on the equation of Tanget al.was higher than that based on the equation of Brown, especially in young- and middle-aged rubber tree plantations.

Aims Litterfall plays an important role in linking aboveground and belowground processes in forest ecosystems. Nutrients absorbed by plants can be released to the soil and re-utilized by plants via litter decomposition. Although litterfall composition and dynamics have been widely studied in the past two decades, the relationship among litterfall, nutrient cycling and vegetation types is poorly understood. Therefore, we studied litterfall in evergreen broad-leaved forests (EBLF) to enrich our knowledge of the relationship.
Methods The research was conducted in Tiantong National Forest Park (29°52'N, 121°39'E, 200 m a.s.l), Zhejiang, East China. We chose secondary and young EBLF (Schima superba community), coniferous and evergreen broad-leaved mixed forest (Pinus massoniana+Schima superba community), coniferous forest (Pinus massoniana community) and shrubland (Lithocarpus glaber + Loropetalum chinense community) to represent forests at different degradation stages and mature EBLF (Castanopsis fargesii community) to represent reference climax forest. Productivity, composition, nutrient concentration and total nutrient amount of the litterfall were measured each month from November 2003 to October 2004. Litterfall traits were correlated with soil total N, total P, total inorganic N, N mineralization and nitrification rates.
Important findings Degradation of EBLF significantly reduced litterfall productivity from 13.03 Mg·hm^-2 in mature EBLF to 6.38 Mg·hm^-2 in shrubland, and significantly reduced N concentration in litterfall. In contrast, P concentration showed no consistent pattern. Total N and total P amounts returned via litterfall decreased significantly with degradation. Soil total N was positively correlated with annual litterfall productivity but not litter N concentration. Soil total P was positively correlated with both annual litterfall productivity and litter P concentration. Soil inorganic N was not correlated with either productivity or litter nutrient concentration. Soil N nitrification rate was positively correlated with annual litterfall productivity and total amounts of nutrients returned, but was not correlated with litter N concentration. Soil N was not correlated with any litterfall traits. These results suggested that, during degradation of EBLF, shifting of plant functional types and simplifying of community structure reduced the quality and quantity of litterfall to a low level and consequently reduced soil nutrient pools.

To advance our understanding of the effects of climate change on grassland ecosystems, we used a time series (1982-1999) data set of the Normalized Difference Vegetation Index (NDVI) together with historical climate data to analyze interannual variations in grassland vegetation cover and explore the relationships between NDVI and climatic factors on the grasslands of the Tibetan Plateau. The NDVI increased significantly by a ratio of 0.41% a^-1 and a magnitude of 0.001 0 a^-1 during the growing season (p=0.015). An increase in NDVI during the growing season resulted from both the advanced growing season and accelerated vegetation activity. The largest NDVI increase was in the spring with a ratio of 0.92% a^-1 and a magnitude of 0.001 4 a^-1. The NDVI increase in the summer was a secondary contributor to the NDVI increase during the growing season with a ratio of 0.37% a^-1 and a magnitude of 0.001 0 a^-1. In the spring, the NDVI increased significantly in the alpine grasslands (alpine meadow and alpine steppe) and temperate steppe (p<0.01;p=0.001; p=0.002). During the summer, a significant NDVI increase was found in alpine meadows (p=0.027). However, the NDVI increase in alpine and temperate steppe was not significant (p=0.106; p=0.087). In the autumn, no significant increase was found in the three grasslands (p=0.585; p=0.461; p=0.143). In the spring, the NDVI increase in three grasslands was corresponded to an increase in temperature. In the summer, the NDVI was related to temperature and sensitive to precipitation in the spring in the alpine grasslands (alpine meadow and alpine steppe). However, no significant statistical relationship was found between NDVI and climatic factors in temperate steppe. Significant lagged correlations between precipitation and NDVI were found for alpine grasslands (alpine meadow, alpine steppe).

This investigation was conducted to determine the quantitative relationship between leaf stomatal conductance and canopy spectral reflectance of rice crops under different water and nitrogen regimes. Results showed that leaf stomatal conductance on main stem leaves under different water treatments decreased in the following order throughout the growth cycle: GsL1 > GsL2 > GsL3 > GsL4. The leaf stomatal conductance in the high nitrogen treatment was higher than in the low nitrogen treatment when the soil water content was above W3. Below W3, there were no significant differences in leaf stomatal conductance between the high and low nitrogen treatments. It also was found that the correlation between the ratio index R(1 650, 760) and stomatal conductance averaged over different layer leaves was the following: GsL1 > GsL12 > GsL123 > GsL1234 > GsL2 > GsL3 > GsL4 (GsL1, GsL2, GsL3, GsL4, GsL12, GsL123 and GsL1234 denoted the first, second, third, fourth leaf and two leaves, three leaves, four leaves from top). The best relationship was between canopy stomatal conductance (the product of GsL1 and LAI) and R(1 650, 760). The ratio index R(1 650, 760) showed a power relationship with both stomatal conductance of L1 and canopy leaf stomatal conductance with an RMSE of 0.05 and 0.24, respectively. It was concluded that the ratio index R can be used to monitor leaf stomatal conductance during different growth stages of rice.

The Gongga Mountain is located on the southeast fringe of the Qinghai-Xizang Plateau, i. e. the middle part of the Great Snow Mountain Range of the Hengduan Mountain Ranges. The Gongga Mountainous region is situated in 29˚20′—30˚00′N. and 101˚30′—102˚10′E., with its main peak being 7556m above sea level. There are 2500 species of vascular plants belonging to 869 genera and 185 families in Gongga Mountainous region. The main floral characteristics of the Gongga Mountainous region are shown as the antiquity of the origin of the floristic composition; marked differentiation of species; abundant endemic species; complex composition and obvious geographical replacement phenomenon. The main vegetation types of the Gongga Mountains are: Subalpine conophorium of Abies, Picea; mid-mountain eonophorium of Pinus and Tsuga; low-mountain conophorium of Pinus, Cunninghamia, Cupressus, and Keteleeria; mixed wood of conophorium and broad-leaf forest of Tsuga, Acer and Betula; evergreen forest of Cinnamomum, Phoebe, Machilus, Lithocarpus and Cyclobalanopsis; deciduous broad-leaf forest of Quercus, Betula, Acer, Populus and Alnus; hard-leaf evergreen forest of Alpine-Quercus; alpine bush-wood of Rhododendron, Salix and Sabina; river-valley busy-wood of Acacia, Opuntia and Bunhinia; alpine meadow and “rock stream” sparse vegetation of Kobresia, Festuca, Allium, Saussurea, Soroseris, etc.The horizontal zones of vegetation in the Gongga Mountainous region is the aiphyllium with the characteristics of the east and west parts of subtropics in China.The vertical belts on the eastern slope are: 1. Evergreen broad-leaf forest belt at alt. 1100—2200m. 2. Coniferous and broad-leaf mixed forest belt at alt. 2200–2500m. 3. Subalpine coniferous forest belt at alt. 2500—3600m. 4. Alpine bush and coryphilum belt at alt. 3600–4600m. 5. Open vegetation belt of alpine “rock stream” belt at alt. 4600–4900m.6. Alpine nival belt at alt. 4900m.The vertical belts on the western slope are: 1. Subalpine coniferous forest belt at alt. 2800—4000m 2. Alpine bush and meadow belt at alt. 4000–4800m. 3. Open vegetation belt of alpine "rock stream" belt at alt. 4800—5100m. 4. Alpine nival belt at alt. 5100m.

Water hyacinth (Eichhornia crassipes) originated in the state of Amazonas, Brazil, spread to other regions of South America, and was carried by humans throughout the tropics and sub-tropics. It is now widespread and recognized as one of the top ten weeds in the world. Water hyacinth has invaded Africa, Asia, North America and Oceania, occurs in at least 62 countries and causes extremely serious ecological, economic and social problems in regions between 40°N and 45°S. Water hyacinth forms dense monocultures and can threaten local native communities, reduce native species diversity, and change the physical and chemical aquatic environment, thus altering ecosystem structure and function by disrupting food chains and nutrient cycling. Water hyacinth has had a great impact on local economic development. The large, dense monoculture formed by this species covers lakes and rivers, thus blocking waterways and interfering with the water transport of agriculture products, tourism activities, water power and irrigation of agricultural fields. Dense mats of water hyacinth can lower dissolved oxygen levels in water bodies and reduce aquatic production, including fish production, thereby reducing fish catches. Annual global costs associated with water hyacinth have increased greatly in recent years. Also, the lifestyles of local people who use and depend on water bodies invaded by water hyacinth have been affected greatly. Water hyacinth is very efficient at taking up calcium, magnesium, sulfur, iron, manganese, aluminum, boron, copper, molybdenum zinc, nitrogen, phosphorus and potassium favoring its growth over other species. When water hyacinth dies, sinks and decomposes, the water becomes more eutrophic due to the large release of nutrients. Water quality can deteriorate, threaten clean drinking water and impact human health. At present, solutions for controlling the spread of water hyacinth are divided into three general categories: physical, chemical and biological control. Biological control has been promoted as the best means for controlling water hyacinth and currently is an important area of research. Biological control includes the utilization of natural enemies, pathogens and allelopaths; however, our knowledge and understanding of the biology and ecology of water hyacinth is limited. To effectively control water hyacinth through biological means, it will be necessary to study more thoroughly the physiology, population and community dynamics, and ecosystem ecology of this species as well as interspecific competition, predation and its evolution. In this paper, we review the costs and benefits associated with the different control methods. We suggest that water hyacinth populations can be reduced and controlled by using an integrated management approach that combines biological control with a watershed management strategy that minimizes pollution and promotes a long term sustainable approach for effective water management in a region.

Microbiome is the combination of all microorganisms and their genetic information in a specific environment or ecosystem, which contains abundant microbial resources. A comprehensive and systematic analysis of the structure and function of microbiome will provide new ideas in solving the core issues in the fields of energy, ecological environment, industrial and agricultural production and human health. However, the study of microbiome largely depends on the development of relevant technologies and methods. Before to the advent of high-throughput sequencing technology, microbial research was mainly based on techniques such as isolation, pure-culture and fingerprint. However, due to the technical restrictions, scientists could only get limited knowledge of microorganisms. Since the beginning of 21st century, the revolutionary advances in the technology of high-throughput sequencing and mass spectrometry have greatly improved our understanding on the structure and ecological functions of environmental microbiome. However, the application of microbiomics technology in microbial research still faces many challenges. In addition, the descriptive studies focusing on the structure and diversity of microbiome have already matured, and the study of microbiomics is facing a critical transition period from quantity to quality and from structure to function. Hence, this paper will firstly introduce the basic concepts of microbiomics and a brief development history. Secondly, this paper introduces the related technologies and methods of microbiomics with their development process, and further expounds the applications and main problems of microbiomics technologies and methods in ecological study. Finally, this paper expounds the frontier direction of the development of microbiomics technology and methods from the technical, theoretical and application levels, and proposes the priority development areas of microbiome research in the future.

The Qinghai Lake region is located in the northeastern of Qinghai-Xizang Plateau, about 36˚15′—38˚20′N,97˚50′—101˚20′E. The elevation of this region is about 3200--5000m about sea level. The vegetation and its distribution in this region was influenced by the existence of Qinghai Lake and the complicated landscape characteristics. Plant species growing in the area is poor. According to preliminary statistics, there are 52 families, 174 genera, 445 species of spermatophytes. The main vegetation types are. needleleaf forest in cold temperate, shrubs in plateau valley, alpine shrubs, sandy shrubs, steppe in temperate, alpine steppe, alpine meadow, swamp meadow, subnival vegetation, and so on. The characteristics of the communities above are described in this paper. The distributional law of vegetation in this region is evident. The horizontal variation of vegetation shows a trend of adapting high-cold habitats from east to west. The temperate steppe, which is distributed in a ring-shaped belt around the lake, is related to the lake basin landscape and the existence of Qinghai Lake. The alpine steppe is found within high-cold habitats. The vertical spectrum in this area from down to up shows steppe-alpine shrubs and alpine meadow-subnival vegetation.As a whole, the region belongs to one part of Qilian Mountains area, and is between the eastern region in Qinghai Province and Qaidam Basin. Based on analysis, vegetation and distribution in Qinghai Lake region has a special pattern and coincides with the climate trends to colder and droughter with the uplift of Qinghai-Xizang Plateau. With all these in mind, we suggest that the Qinghai Lake region, is a relatively independent part of Qilian Mountains area.

Aims Cropping practices and fertilizer/organic matter application affects the soil microbial growth and activity. In china, only few studies have been conducted on the influence of long-term fertilizer and organic matter with fertilizer application on the soil biological properties. Our objective was to study the changes in soil biological and biochemical characteristics under a long-term (15 years) field experiment involving fertility treatments (inorganic fertilizers and organic matter with fertilizers) and two crop rotation systems.
Methods In 1990, thirteen different treatments were established in the Drab Fluvo-aquic soil in Beijing for the long-term experiment. Six treatments were chosen in this study. Four were in a wheat-maize rotation receiving no fertilizer (CK), mineral fertilizers (NPK), mineral fertilizers plus farmyard manure (NPKM) and mineral fertilizers with maize straw incorporated (NPKS). One was in a wheat-maize/wheat-soybean rotation receiving NPK (NPKF). The other was abandoned arable land (CK0) growing weeds. The amount of chemical fertilizer per year was N 150 kg·hm^-2, P₂O₅ 75 kg·hm^-2, K₂O 45 kg·hm^-2, manure 22.5 Mg·hm^-2 and maize straw 2.25 Mg·hm^-2. Established methods were used to analyze soil enzymes and soil physical and chemical characteristics. Analysis was done using an integrative method combining correlation and component analyses in SPSS.
Important findings The soil organic C (SOC) and total N (STN) content, microbial biomass C (SMB-C) & N (SMB-N), activities of soil invertase, phosphatase and urease, and the ratio of SMB-C/SOC and SMB-N/STN were found higher in long-term (15 years) abandoned arable land than those in cultivated arable land soils. However, the soil metabolic quotient, pH value and bulk density of fallow soil were lower than those in cultivated arable land soils. The soil nutrient concentration, microbial biomass C & N, activities of soil invertase, phosphatase and urease, were higher in treatments with fertilizer application (NPK, NPKM, NPKS and NPKF) compared to no fertilizer application treatment (CK). The above soil parameters were also found higher in wheat-maize/wheat-soybean rotation cropping system compared to continuous wheat-maize cropping system. Among the fertilizer application treatments (NPK, NPKM, NPKS and NPKF), NPKM had relative higher soil nutrient concentration, microbial biomass C & N, and enzyme activities compared to other fertilizer application treatments. However, the soil metabolic quotient, pH value and bulk density of NPKM were lower than them.

The analyses of spatial distribution patterns of plant populations are useful for understanding pattern types and intra/inter-specific relationships. One of the most frequently employed methods in detecting spatial distribution patterns of populations is the nearest neighbor analysis proposed by Clark and Evans in 1954. This method has been highly successful for analyzing spatial patterns at a single scale but is rarely used for analyzing distribution patterns at multiple scales. We present the extended nearest neighbor analysis (ENNA) in this paper to solve the scale-dependent problem associated with the traditional method of nearest neighbor analysis. The Clark-Evans index was modified by using a distance scale parameter d (m), described in the following equation: CE (d) =r dA /r dE = (1N d∑N di=1r di ) / (0.5A d/N d+0.051 4P d/N d+0.041P d/N d 3/2 ). Accordingly, the equation for testing the calculated CE index values against the significant deviation from 1 was changed into u (d) = (r dA -r dE ) /σ d, where the parameters, r dA, r dE, N d, r di, A d, P d, σ d, refer to the mean distance between an individual and its nearest neighbor (m), the expected mean distance of the individuals of a population randomly scattered (m), the number of individuals in the current sample plot, distance between individual i and its nearest neighbor (m), surface of the current sample plot (m 2), circumference of the current sample plot (m), and the standard deviation, respectively. The procedure of scaling transformation in this approach was similar to that of the sandbox experiment in fractal theory, and the rule for detecting the pattern type was the same as that in the traditional nearest neighbor analysis. The traditional nearest neighbor analysis is a special case for the extended nearest neighbor analysis in which the minimum value of the distance scale parameter (d) is used. An example using the data from a needle and broad-leaved mixed forest community at Heishiding Nature Reserve, Guangdong Province was presented to explain the procedure. Five typical plant populations of this community, Pinus massoniana, Symplocos laurina, Castanopsis nigrescens, Itea chinensis and Rhodomyrtus tomentosa, were chosen for the multi-scale analysis of spatial distribution patterns. The results showed that spatial patterns of all five populations were scale-dependent with varying degrees of intensity. The Pinus massoniana population was randomly distributed at most scales examined, which may have been caused by the random self-thinning process in the population. The population of Itea chinensis was clumped at all scales examined. A simulation with the aid of geographic information system (GIS) also revealed that the distribution patterns of Symplocos laurina, Castanopsis nigrescens, Itea chinensis and Rhodomyrtus tomentosa were mainly clumped or random with an increase of distance scale. These results demonstrated that the ENNA method presented in this paper could be used for multi-scale analysis of spatial distribution patterns of plant populations that could not be solved using the traditional nearest neighbor analysis.

Aims Soil respiration may have distinct dynamic patterns at different temporal scales since it is affected by diverse abiotic and biotic factors. Seasonal variation in soil respiration is largely controlled by abiotic factors such as temperature and soil moisture, whereas the regulation of diurnal variation is likely physiological rhythms of plants. Our objectives were to compare seasonal and diurnal patterns of soil respiration and to evaluate relationships between soil respiration and temperature at annual and diurnal scales.
Methods We examined seasonal variations of soil respiration using infrared gas analyzers at monthly or bimonthly intervals from April 2004 to March 2005, and diurnal variations in July, September and November 2004 as well as in January, March and May 2005 in a montane evergreen broad-leaved forest in Ailao Mountains, China. Soil temperature, air temperature, soil water content and air humidity were measured at the same time. We evaluated Q₁₀ values of soil respiration and correlations between soil respiration and soil temperature.
Important findings Soil respiration fluctuated with distinct seasonal and diurnal patterns. Soil respiration was higher in the wet season (May through October) than in the dry season (November through April). Diurnal patterns of soil respiration varied among seasons. The mean rate of soil respiration was higher in nighttime than in daytime in July, September, January and March, but lower in November and May. On the whole-year basis, soil respiration correlated strongly with soil temperature and soil water content. However, on a diurnal scale, these regressions were not significant. Q₁₀ values were 4.48, 7.17 and 2.34 for the whole year, dry season and wet season, and their corresponding soil temperature ranges were 5.9-16.6, 5.9-11.0 and 10.3-16.6 ℃, respectively. Our results demonstrate that biotic and abiotic factors have distinct impacts on soil respiration at different temporal scales in the forest. Estimation on daily and annual carbon fluxes based on instantaneous measurements of soil respiration, rather than 24-hour measurements, may cause severe deviation from actual values because of the lack of diurnal correlation between soil respiration and temperature.

In Chinese botanical literature, the term “tropical monsoon forest” is explained and used inconsistently and is often confused with tropical rain forest. My objective is to clarify differences between the two forests. Schimper defined tropical monsoon forest as being more or less leafless during the dry season and considered it a transitional vegetation type between tropical rain forest and savanna in terms of physiognomy and distribution. I compared tropical monsoon forest and rain forest in physiognomy, floristic composition and geographical elements to describe and characterize the monsoon forest in Yunnan, China. The tropical monsoon forest in Yunnan occurs mainly on river banks and in basins of several large rivers below 1 000 m altitude. The forest has one or two tree layers, and trees of at least the top layer are deciduous in the dry season. In life forms, the forest is rich in hemicryptophytes and relatively rich in geophytes and therophytes, but less rich in woody lianas and almost lacks megaphanerophytes and chamaephytes compared to tropical rain forest. In leaf size and form, the forest has more microphyllous leaves and compound leaves (24% and 44% of tree species, respectively) than tropical rain forest. In terms of floristic elements, the forest has a greater percentage of species of pantropic distribution (30% of the genera) and tropical Asia and tropical Africa disjunct distribution than tropical rain forest. Thus, the tropical monsoon forest in Yunnan has more diverse geographical elements in its flora and a complicated evolution history.

The stability of ecosystems determines whether they can sustainably provide key functions and services in the background of global changes. Ecosystem stability, particularly its relation with biodiversity, is one of the central issues in ecology. Whether biodiversity enhances or impairs ecosystem stability has historically aroused much debate. Based on early reviews and studies on different aspects of stability, here we summarized recent advances from three aspects. Firstly, several recent theoretical studies offered novel insights in understanding the multi- dimensionality of stability and the intrinsic link between different stability measures, and we provided an overview on these new insights. Secondly, we reviewed recent empirical and theoretical studies on biodiversity- stability relationships, including those in the context of multidimensional stability. Thirdly, we introduced the recently developed multi-scale stability framework, which provides new opportunity to understand the scaling of stability and extend diversity-stability relations to a multi-scale context. We ended with a discussion on future research questions and directions.

In order to understand the research progress of litter decomposition and its underlying mechanisms, this paper presented a bibliometric analysis of litter decomposition in China from 1986 to 2018 based on the four common literature databases, including CNKI, ISI Web of Science, ScienceDirect and Springer Link. Litter decomposition researches are mainly from forest ecosystems (65%), and focus on above-ground litter. This suggests that the studies on below-ground litter decomposition should be strengthened in the future. About 68% studies focused on the litters from dominant species, which couldn’t represent the natural decomposition characteristics due to the mixed effects among litters from multiple species. Besides carbon, nitrogen and phosphorus, we should pay more attention to other key chemical components related with decomposition (e.g. K, Fe, Mn, lignin, tannin, etc.) and the heavy metal elements related with environmental pollution. Meanwhile, ecological stoichiometry is an effective method to interlink the biogeochemical cycle in the plant-litter-soil system. Nitrogen deposition and climate change are hot topics in the field of litter decomposition, especially the interactions of multiple factors (e.g. nitrogen, phosphorus, etc.), temperature sensitivity of litter decomposition and underlying mechanisms in permafrost under climate warming context.

The biological sciences developed very fast during the 20th century and have become increasingly sophisticated and predictive. Along with this trend, areas of research also have become increasingly specialized and fragmented. However, this fragmentation and specialization risks overlooking the most inherent biological characteristics of living organisms. One can ask if the living organisms on the earth have unified and essential characteristics that can connect the disparate disciplines and levels of biological study from molecular structure of genes to ecosystem dynamics. By exploring this question, a new science, ecological stoichiometry, has been developed over the past two decades. Ecological stoichiometry is a study of the mass balance of multiple chemical elements in living systems; it analyzes the constraints and consequences of these mass balances during ecological interactions. All biological entities on the earth have a specific elemental composition and specific elemental requirements, which influence their interactions with other organisms and their abiotic environment in predictable ways. Ecological stoichiometry has been incorporated successfully into many levels of biology from molecular, cellular, organismal and population to ecosystem and globe. At present, the principles of ecological stoichiometry have been broadly applied to research on population dynamics, trophic dynamics, microbial nutrition, host-pathogen interactions, symbiosis, comparative ecosystem analysis, and consumer-driven nutrient cycling. This paper reviews the concepts, research history, principles, and applications of ecological stoichiometry and points out future research hotspots in this dynamic field of study with an aim to promote this discipline of research in China.

Crofton weed gall fly (Procecidochares utilis) has been used widely as a natural enemy to control the invasive plant, crofton weed (Eupatorium adenophorum), but the effectiveness and mechanisms of crofton weed gall fly in controlling and preventing the weed have not well been studied. In this paper, we surveyed parasitism of gall fly on crofton weed in ecosystems that had been damaged by crofton weed in the western Panzhihua Prefecture, Sichuan Province, Southwest China. We studied the effects of the gall fly on the growth and reproduction of crofton weed by comparing the parasitism rates of individuals and branches with different ages in different habitats. The diameter, quantity of blossom branches, capitula and seeds between parasitized and normal branches also were compared. The results showed that: 1) there were significant differences (p<0.05) in the parasitism rates based on individuals (71.67%) and branches (17.30%). There were, on average, 17.48 parasitized branches per square meter in the adult population; branches with one insect gall accounted for 92.30% of the total parasitized branches. 2) The parasitism rate of branches (20.27%) in the humid habitat was markedly higher than that in the drought habitat (p<0.05). 3) The parasitization rate of branches differed significantly among individuals of different ages. Parasitism rates of seedlings (36.36%) and one-year-old individuals (21.56%) were significantly higher (p<0.05) than older individuals (13.50%, 8.82%, and 12.16% for two-year, three-year, and four-year old individuals). 4) Crofton weed gall fly had no significant effect on the diameter of branches, quantity of blossom branches, capitula or seeds of crofton weed, suggesting that parasitism of crofton-weed gall fly would not impact the growth and reproduction of crofton weed.

The invasion of Eupatorium adenophorum has caused serious damage to natural ecosystems by suppressing native species populations in disturbed forests and pastures in southwest China. In this study, the age structure dynamics of E. adenophorum populations were examined in 20 plots (10 m × 10 m) using the Greig-Smith grid method, in Panzhihua Prefecture, Sichuan Province of China. There is no standard method for identifying the age of an E. adenophorum plants, but through careful observations of the growth characteristics of E. adenophorum over several years in Panzhihua, we found a reliable method for aging individual plants. During the coldest season of every year, the apical half of branches grown in the current year wither and die, and a pair of opposite branches expand out from the lignified half that is below the wilted top. Although it can turn out clone genet alone once the branch touches the ground. At the same time sexual propagation and vegetative reproduction of radicicolous branches carry through from year to year. That is to say, the most number of branching ranks of the same branch is likely to indicate the real age of the plant. We dug out the entire plant in each grid and counted the grade rank of each branch to determine the age of each individual plant. The results showed that the age structure of the 4 populations were similar with most individuals in the infancy (92.3%) and youth (6.4%) periods. The analysis of life tables and survival curves showed that chronological sequence of an E. adenophorum invasion was as follows: first, invasion occurred along roadside fields, followed by invasion into the margins of broad-leaved forest, then deep into broad-leaved forest, and finally into Pinus yunnanensis forest. Even under different environmental conditions, survival curves of all E. adenophorum populations belonged to the Deevey type Ⅲ pattern, and mortality of all populations showed a peak in 1-2 years old with mortality rates of 97.3%. The degree to which a population deviated from a typical curve related to the intensity of human disturbance. In general, mortality during infancy period and mature period were high (93.1% and 92.0%). The invasion time-sequence model predicts that young and mature individuals will dominate the populations at 3 and 5 years from the present. Therefore, in the Panzhihua Prefecture, we predict that E. adenophorum will become a serious problem in 3 to 5 years. Compared with populations of other invasive plants, the population of E. adenophorum has a similar break out pattern among populations. Traits promoting weediness included the ability to reproduce sexually and asexually, rapid growth from seedling to sexual maturity, and, most importantly, adaptation to environmental stress (phenotypic plasticity) and high tolerance to environmental heterogeneity.

Aims It is well documented that nitrogen (N) and phosphorus (P) are the two main growth-limiting nutrients for plants in many natural environments. Plant N:P ratio has proved useful as an indicator of shifts from N (P) to P (N) limitation because it is easily determined and compared. However, little is known about the plant N:P ratio in evergreen broad-leaved forests (EBLF), particularly the pattern along secondary succession. Therefore, our goal was to examine the relationship between the form of nutrient limitation and secondary successional stage by using the N:P ratio of plant leaves (ratio of N to P concentration) as an indicator.
Methods The research was completed in Tiantong National Forest Park (29°52' N, 121°39' E, 200 m elevation), Zhejiang Province, East China. Leaf N and P concentrations of dominant tree species along a secondary succession gradient of EBLF were quantified to provide canopy N:P ratios for different communities. Leaf N and P concentrations of common plant species in a given community were then determined to emphasize the relationships between differences in the N:P ratios among species at each successional stage.
Important finding Shifts in the N:P ratios of species were consistent along the successional series, although the N:P ratios of different species in a given community varied considerably. At the community level, the lowest N:P ratio (7.38) was found in grassland, which was usually considered a primary stage of EBLF succession. Thereafter, the N:P ratio increased to 19.96 in the shrub stage, declined to an average of 14-16 in the mid-stages of succession, including coniferous forest and coniferous-broadleaved mixed forest, and increased at the end stages of succession (e.g. 18.77 in the Schima superba community and 20.13 in the Castanopsis fargesii community). These results suggest that the productivity of vegetation in the Tiantong region is N-limited in the primary stages of succession, N- and P-limited in the mid-succession stages and probably P-limited in the shrub and mature EBLF stages.

The solution of lead acetate was applied in the soil or spread on the leaves of sweet potatoes and egg-plants grown in pots to investigate its effects, accumulation and translocation within the plants.It was shown that even though very high concentration of lead was treated either in the soil or on the foliage, no visible injury symptoms had been found. It indicated that plants were rather tolerant to lead impact. Lead acetate solution applied in the soil could be absorbed by the roots and most of the lead remained in the roots, and the solutions spread on the leaves could be absorbed by the leaves and most of the lead remained in the leaves. Only a little amounts of lead could be translocated from roots to stems and leaves or from leaves to stems, roots and nontreated leaves. Very little lead was translocated into the fruits of egg-plant and the root tubers of sweet potato especially the edible parts of them (the pulp and starch).

The concept of nitrogen use efficiency (NUE) offers a powerful tool to study plant strategies with respect to nutrient limitation. We studied the NUE of an annual herb, Chenopodium album, in a dense monospecific stand using the concept introduced by Berendse and Aerts. Larger individuals absorbed more N in greater proportions relative to their size, suggesting that the competition for soil nitrogen was asymmetric (one-sided) among individual plants in the stand. Nitrogen loss from individuals also increased with plant size. Nitrogen influx (rin, the rate of N uptake per unit aboveground N) was greater in larger individuals while nitrogen outflux (rout, the rate of N loss per unit aboveground N) was the reverse. Therefore, the relative rate of nitrogen increment (rin-rout) was greater in larger individuals whereas it was around zero in the smallest plants. Larger individuals decreased their N concentration with time while smaller individuals showed little change in N concentration. These results suggested that the growth of smaller individuals was limited by light availability rather than by N availability, and N limitations were greater in larger individuals. Individual plants in this dense stand of C. album differed in their N economy. NUE and its components, i.e., MRT and NP, were different among individuals in the stand. Both NP and MRT were positively related to plant size. Larger individuals had longer MRT and higher NP, both of which contributed to higher NUE, than the smaller individuals. No trade-off relationship between NP and MRT was found at the intraspecific level. This study showed that the concept of NUE defined by Berendse and Aerts offered a powerful tool in studing plant strategies within species as well as among species.

Natural systems are essentially complex. In most cases, fully understanding natural systems requires the capacity to examine simultaneous influences and responses among multiple interacting factors. Compared with traditional multivariate methods, structural equation model (SEM) could specify the causal or dependent relationships among variables using the prior knowledge of researchers before conducting relevant experiments, i.e. initial models. SEM could not only identify the individual path coefficient for each relationship, but also estimate the whole model fit to determine whether to revise the initial models. We attempt to introduce SEM from the following aspects: definition and types of variables in SEM, detailed procedures for how to analyze data through SEM, some applications of SEM in ecology and recommended software. We encourage more researchers to apply SEM in ecological data analyses in order to improve understanding of natural systems and advance the field of ecology.

Leaf is one of the important organs of plants that facilitates the exchange of water and air with the surrounding environment. The morphological variation of leaves directly affect the physiological and biochemical processes of plants, which also reflects the adaptive strategies of plants to obtain resources. By focusing on several leaf morphological traits, including leaf size, leaf shape, leaf margin (with or without teeth) and leaf type (i.e. single vs. compound leaf), here, we reviewed the relevant research progresses in this field. We summarized the ecological functions of leaf morphological traits, identified their geographical distribution patterns, and explored the underlying environmental drivers, potential ecological interactions, and their effects on ecosystem functioning. We found that the current studies exploring the distribution and determinants of leaf size and leaf margin states mainly focused on single or specific taxon in local regions. Studies have also explored the genetic mechanisms of leaf morphology development. Leaf traits trade off with other functional traits, and their spatial variation is driven by both temperature and water availability. Leaf morphological traits, especially leaf size, influence water and nutrient cycling, reflect the response of communities to climate change, and can be scaled up to predict ecosystem primary productivity. Further studies should pay attention to combine new approaches to obtain unbiased data with high coverage, to explore the long-term adaptive evolution of leaf morphology, and to generalize the scaling in leaf morphology and its effect on ecosystem functioning. Leaf provides an important perspective to understand how plants respond and adapt to environmental changes. Studying leaf morphological traits provides insight into species fitness, community dynamics and ecosystem functioning, and also improves our understanding of the research progresses made in related fields, including plant community ecology and functional biogeography.

Estimating carbon storage in terrestrial ecosystems has been a central focus of research over the past two decades because of its importance to terrestrial carbon cycles and ecosystem processes. As one of the most widespread ecosystem types, China’s grasslands play an important role in global change research. The grasslands in China, which are distributed primarily throughout the temperate regions and on the Tibetan Plateau, were classified into 17 community types. In the present study, a statistical model was established to estimate grassland biomass and its geographical distribution in China based on a grassland inventory data set and remote sensing data (Normalized Difference Vegetation Index) using GIS and RS techniques. We found that there was a significant correlation between aboveground biomass density and the maximum annual NDVI when expressed as a power function (R2=0.71, p<0.001). The aboveground biomass was estimated to be 146.16 TgC (1Tg=1012 g) and belowground biomass was estimated as 898.60 TgC (6.15 times of the above biomass) for a total biomass of 1 044.76 TgC. This value accounts for about 2.1%-3.7% of the world’s grassland biomass. The grassland biomass is distributed primarily in the arid and semiarid regions of Northern China and the Qinghai-Xizang Plateau. The average biomass density of China’s grasslands was 315.24 gC·m-2, smaller than the world average. The aboveground biomass density decreases from southeastern China toward the northwest corresponding with changes in precipitation and temperature. Furthermore, aboveground biomass density reached the lowest levels at 1 350 m elevation and peak levels at 3 750 m above sea level which most likely is related to China’s three-step topographical background. The ratio of total biomass of grassland to forest biomass in China is 1/4, much higher than that of the world, suggesting a greater contribution of grasslands to China’s carbon pool.

Aims Shorea wantianshuea is an endangered tree species of Dipterocarpaceae in Xishuangbanna seasonal rain forest, and is listed in the Plant Red Book under Grade Ⅰ in China. This species regenerates exclusively from seeds. Our objective was to determine the fate of seedlings (including their growth and survival) following a mast fruiting event. Results will be useful in restoring this species and degraded natural forests dominated by it.
Methods In early December 2004, after mast fruiting of S. wantianshuea, we established three parallel 20 m×100 m transects spaced 50 m apart within an area of 100 m×200 m spanning from valley bottom to ridge top. Each transect was stratified into five contiguous plots of 20 m and near the center of each plot two 3 m×3 m quadrats were established. We labeled all newly established S. wantianshuea seedlings in each quadrat, recorded seedling height, basal stem diameter and number of leaves every 2-3 months over a 10-month period and calculated death rate, herbivory rate and survival rate of the seedlings. At the end of the survey, we destructively sampled seedlings and determined leaf areas, total dry weight, root-shoot ratio and specific leaf area.
Important findings Many S. wantianshuea seedlings established after the mast-fruiting event did not recruit into its natural population because of high mortality rate and herbivory rate caused by seasonal drought stress, small mammals and other predators. The density of seedlings was as high as 2.76 plants·m^-2 in December 2004 (first census), but was less than 0.26 plants·m^-2 in September 2005 when the study ended. Seedling mortality rate was high during the dry season, particularly after the first two months. The final seedling mortality rate on ridge-top and lower-ridge sites, 55% and 54%, respectively, were higher than those on other sites, with a gradually increase from valley bottom to ridge top. Herbivory rate in the first census was low and in 8 of 15 sites no seedlings were gnawed or pulled. At the end of the study, mean seedling height was 17.9, 19.7, 18.4, 13.0 and 12.1 cm in valley-bottom, lower-slope, medium-slope, lower-ridge and ridge-top sites, respectively; however, no significant differences were observed in seedling height and other growth parameters.

Root exudates have specialized roles in nutrient cycling and signal transduction between a root system and soil, as well as in plant response to environmental stresses. They are the key regulators in rhizosphere communication, and can modify the biological and physical interactions between roots and soil organisms. Root exudates play important roles in biogeochemical cycle, regulation of rhizospheric ecological processes, and plant growth and development, and so on. Root exudates also serve roles in the plant-plant, plant-microbe, and microbe-microbe interactions. Plant allelopathy, intercropping system, bioremediation, and biological invasion are all the focal subjects in the field of contemporary agricultural ecology. They all involve the complex biological processes in rhizosphere. There are increasing evidences that various positive and negative plant-plant interactions within or among plant populations, such as allelopathy, consecutive monoculture problem, and interspecific facilitation in intercropping system, are all the results of the integrative effect of plant-microbe interactions mediated by root exudates. Recently, with the development of biotechnology, the methods and technologies relating to soil ecological research have achieved a remarkable progress. In particular, the breakthroughs of meta-omics technologies, including environmental metagenomics, metatranscriptomics, metaproteomics, and metabonomics, have largely enriched our knowledge of the soil biological world and the biodiversity and function diversity belowground. Research on plant-soil-microbe interactions mediated by root exudates has important implications for elucidating the functions of rhizosphere microecology and for providing practical guidelines. The concept and components of root exudates as well as the functions are reviewed in this paper. An overview on the root-bacteria, root-fungi, and root-fauna interactions is presented in detail. Methods to study root exudates and microbial communities are reviewed and the aspects needed to be further studied are also suggested.

Climate warming is one key issue of global change and plays an important role on carbon cycling in terrestrial ecosystems. This paper reviews the recent advance in our understanding of global warming and its impacts on terrestrial carbon cycling and underlying mechanisms. We also discuss the state-of-the art in ecosystem modeling and its applications to ecosystem assessment. Climate warming will influence terrestrial carbon cycling in several aspects: 1) net primary productivity (NPP) will decrease in low-latitude region, and increase in mid- and high-latitude zones, totally show an increase on the global scale; 2) soil respiration will increase at the initial stage and then keep relatively stable because of biotic adaptability; 3) plant carbon storage will increase in high-latitude region, and remain stable or even decrease in low-latitude zone, and show a slight increase on the global level; 4) the production and decomposition rate of litterfall will increase; 5) the decomposition rate of soil organic carbon will increase and thus decrease soil carbon stock, meanwhile, soil carbon stock will increase for more carbon input from plant litter. These two processes will trade off in certain degree, resulting in different results for varied ecosystems. On the global scale, soil carbon stock will show a decrease; 6) although the different performances of diverse ecosystems, the global terrestrial ecosystem acts as a weak carbon source. Biophysical, biogeographical and biogeochemical models were developed in the past decades for global change research. In the future research, there are an urgent need to address the interaction among climate warming and other factors including elevated CO₂, O₃, drought, fire disturbance. The big challenge we are facing is how to deal with the complexity with multi-factors and multi-scales by using experimental and modeling approaches.

We present a soil carbon budget for a grazed Leymus chinensis steppe community in the Xilin River basin of Inner Mongolia based on historical data and current field measurements. The study site was situated in the southern part of the basin, approximately 1 265 m above sea level. The climate is temperate and semi-arid with a mean annual rainfall of 350 mm and annual mean temperature of 0.3 ℃. The dark chestnut soil profile is about 1 m in depth with a 10-20 cm thick humus layer, a pH of 7.4 to 8.3, and an organic C content of 1.53%-1.37% in the upper 0-20 cm layer. A grazed stand (43°32′58″ N, 116°40′34″ E) outside the L. chinensis permanent plot of the Inner Mongolian Grassland Ecosystem Research Station was chosen as a sampling plot. Vegetation consisted mainly of L. chinensis, Stipa grandis, Agropyron cristatum, and Cleistogenes squarrosa, which accounted for 80% of the total aboveground biomass. The pasture has been grazed continuously for more than 40 years at a moderate stocking rate with about 2/3 of the above-ground biomass consumed annually.Soil respiration, and aboveground biomass, and root biomass measurements were initiated May 31, 1998 and measured every ten days over two growing seasons until October 14, 1999. The alkali absorption method was used to measure soil respiration. Root respiration was evaluated indirectly by relating the amount of root biomass under the chamber to rates of CO2 evolution. Aboveground biomass was measured in 10-25 cm diameter circular plots using the harvest method. The maximum biomass value measured during the growing season was taken as the annual net primary productivity (NPP). Root biomass was measured to 30 cm depth, and the root productivity was estimated using the annual increment of growth, as defined by Dahlman and Kucera. Food consumption by insects was determined using the cage-feeding method by using a series of cages with different insect population densities.The annual average carbon input from aboveground biomass production was 78.2 gC·m-2·a-1, and inputs from root biomass to 30 cm depth averaged 322.5 gC·m-2·a-1. The summed mean annual carbon input of shoot and root materials was approximately 400.7 gC·m-2·a-1. The annual amount of aboveground biomass consumed by insects averaged 14.7 gC·m-2·a-1, and the carbon output by leaching or light-chemical oxidation was 3.2 gC·m-2·a-1. The annual evolution rate of CO2 from net soil respiration averaged 343.7 gC·m-2·a-1. Cattle consumption was 49.7 gC·m-2·a-1. The summed mean annual output was approximately 411.3 gC·m-2·a-1 and a net carbon release of about 10.6 gC·m-2·a-1 was calculated. Based on the soil organic carbon density of the field, the turnover rate of soil carbon in 0-30 cm depth was 6.2%, with a turnover time of 16 years.Carbon budgets for each of the two years, 1998 and 1999, were quite different. A net carbon release of 75.1 gC·m-2·a-1 was detected in 1999, while a net carbon accumulation of 54.1 gC·m-2·a-1 occurred in 1998. By comparing carbon cycling patterns between 1998 and 1999, it was evident that the difference between years arose primarily from differences in root production and soil respiration between the two years. Severe drought in 1999 and record high rainfall in 1998 caused a difference in root NPP by as much as 220.5 gC·m-2·a-1. The root NPP accounted for about 73%～85% of the total carbon input in the community, indicating the importance of the belowground biomass in estimating the carbon budget for this ecosystem. Soil respiration seemed to be less sensitive to drought, with only about a 22.5% decrease in 1999 whereas root NPP decreased by about one half in 1999. Our results indicated that drought, a frequent occurrence in this region, could change this ecosystem from a sink to a source for atmospheric CO2. The degree to which this grassland could become a source of CO2 appeared to depend also on the stocking rate.

Aims Parashorea chinensis, an endangered plant listed as the first class protected in China, now survives in local fragmented forests in Mengla, Hekou in Yunnan and Bama, Tianyang, Longzhou, Napo in Guangxi. We developed regression models for individual growth, age structure and biomass and analyzed population density, age structure, biomass dynamics and survivorship curves for local populations and the entire population in Mengla, Xishuangbanna, Yunnan Province, SW China. Our objective was to understand the population dynamics to aid protection of this endangered plant.
Methods We established different numbers and sizes of plots (50 m × 20 m or 100 m × 20 m ) in five local patches according to patch size, and each plot was divided into 10 m × 10 m subplots to measure the height, diameter at breast height (DBH) or basal diameter and crown of each individual >0.5 m height. We also measured height, basal diameter and crown of each individual <0.5 m height in 2 m × 2 m quadrats in each subplot.
Important findings There were large differences in population density and age structure as well as mortality rate for different age stages of local populations in different patches. The local population density of the patch in which some trees were cut was 3-4 times as much as the patch which was protected and 16 -18 times as much as the patch which was planted with Amomum villosum. Moreover, the local population of the smallest patch had no mature individuals and lacked individuals in some age stages. Although the biomass of local populations showed logistic increase with stand age, maximum biomass and biomass dynamics with time were different for local populations. The survivorship curve of the entire population was approximately a straight line, indicating that the age structure of entire population was stable and increasing. The mortality of 1-60 year-old individuals declined, mortality of 60-150 year-old individuals increased with age, and peak mortality occurred after 180 years. The biomass of the entire population was consistent with logistic growth before 180 years and was at a maximum at about 180 years. However, some patches had been so badly disturbed that the local populations were on the edge of extinction. Effective steps must be taken to protect this endangered plant population.

Water is a vital resource for plant survival, growth and distribution, and it is of significance to explore mechanisms of plant water-relations regulation and responses to drought in ecophysiology and global change ecology. Plants adapt to different climates and soil water regimes and develop divergent water-regulation strategies involving a suite of related traits, of which two typical types are isohydric and anisohydric behaviors. It is critical to distinguish water-regulation strategies of plants and reveal the underlying mechanisms for plant breeding and vegetation restoration especially in xeric regions; and it is also important for developing more accurate vegetation dynamic models and predicting vegetation distribution under climate change scenarios. In this review, we first recalled the definitions of isohydric and anisohydric regulations and three quantitative classification methods that were established based on the relationships (1) between stomatal conductance and leaf water potential, (2) between stomatal conductance and vapor pressure deficit, (3) between predawn and midday leaf water potentials. We then compared the two water-regulation strategies in terms of hydraulics and carbon-economics traits. We synthesized the mechanisms of plant water-regulation and found that the interaction between hydraulic and chemical signals was the dominant factor controlling plant water-regulation behavior. Last, we proposed three promising aspects in this field: (1) to explore reliable and universal methods for classifying plant water-regulation strategies based on extensive investigation of the traits related with plant water-relations in various regions; (2) to explore relationships between plant water-regulation strategies and traits of hydraulics, morphology, structure, and function in order to provide reliable parameters for improving vegetation dynamic models; and (3) to deeply understand the processes of plant water-regulation at different spatial and temporal scales, and reveal mechanisms of plants’ responses and adaption to environmental stresses (especially drought).

Nitrogen availability is a major determinant of successional patterns in many ecosystems. Increased levels of soil nitrogen, caused by atmospheric nitrogen deposition, continuously fertilize a large (and growing) portion of the terrestrial biosphere. Increased nitrogen deposition onto natural ecosystems is disadvantageous to slow-growing native plants that have adapted to nutrient-poor habitats by creating environments favorable for faster-growing plants, such as grasses. In this paper, two invasive plant species, Ageratina adenophora and Chromoleana odorata, were studied. Both of them were planted under five soil nitrogen levels for more than four months. By investigating their traits related to morphology, biomass allocation, growth and photosynthesis, we compared their phenotypic responses to nitrogen. Our main objectives were to 1) explore how the two species acclimate to soil nitrogen availability, 2) evaluate which plant traits were associated with the invasiveness of the two species, and 3) determine whether the increased levels of soil nitrogen could facilitate their invasion.
The two species were very plastic in their response to nitrogen availability. They exhibited considerable (nitrogen-acclimation abilities. With an increase in nitrogen levels, their root mass ratio and root mass/crown mass decreased, but their leaf mass ratio (LMR), leaf area ratio and leaf area to root mass ratio increased. At lower nitrogen levels, more biomass was invested into the root system, a nutrient absorbing organ, which could enhance nutrient-capture ability. At higher nitrogen levels, more biomass was invested into the leaves, an assimilative organ, which could increase their carbon accumulation and improve their competitive abilities. A. adenophorum could acclimate better to nitrogen environments than C. odorata.
The two invasive plant species could benefit from high nitrogen levels, which were usually excessive and/or harmful for most native species. Under a wide range of nitrogen levels, relative growth rates (RGR), total biomass, branch numbers, leaf area index, maximum net photosynthetic rate, chlorophyll and carotenoid content increased significantly with increasing nitrogen levels, and did not decrease significantly at over-optimal nitrogen levels. The two species could maintain relatively higher RGR in the dry season when native plant species almost stopped growing. Having the ability to use resources at times when native plants could not, their competitive abilities and invasiveness were promoted.
Mean leaf area ratio (equal to LMR/SLA (specific leaf area)) and net assimilation rate were coequally important in determining the response of RGR to nitrogen levels in A. adenophora and C. odorata. LMR was a very important determinant of RGR, which played the most important role in determining differences in RGR among nitrogen treatments and between species. With an increase in nitrogen levels, the SLA decreased in A. adenophora whereas it increased in C. odorata. But under all nitrogen levels, SLA was higher in A. adenophora than in C. odorata. The higher SLA of A. adenophora compensated this species for its lower LMR and was favorable to its growth. The response trend of SLA to nitrogen levels in A. adenophora was more profitable than in C. odorata.
In conclusion, our results indicated that the two invasive plant species were able to acclimate to a wide range of nitrogen environments and could grow better in higher nitrogen environments, suggesting that enhanced soil nitrogen levels might promote their invasion.

Over the recent decade, biodiversity and ecosystem multifunctionality (BEMF) has aroused as an emerging reserach hotspot in the filed of biodiversity and ecosystem functioning. Ecosystem multifunctionality is defined as the capacity of an ecosystem to provide multiple ecosystem functions simulateneously, it has received broad consideration by community and ecosystem ecologists. In this study, we first conducted a literature review of the research history in biodiversity and ecosystem multifunctionality. Next, we summarized the major trends in biodiversity and ecosystem multifunctionality research including the impacts of biodiversity dimensions, global change drivers and spatial-temporal scales on ecosystem multifunctionality. We reviewed the new research methods and research directions emerged in the field. We also defined a new concept, i.e., ecosystem multiserviceability (EMS) based on the distinction between ecosystem functions and ecosystem services. Finally, we briefly summarized the limitations in current research of biodiversity and ecosystem multifunctionality/multiserviceability (BEMF/BEMS) and presented the outlook for future study.